This application proposes: 1. The synthesis and characterization of several plasmids carrying tRNA genes, and studies of their effects on RNA synthesis. 2. Studies on the synthesis of large, single-subunit aminoacyl-tRNA synthetases. 3. The sequencing and physiological characterization of regulatory mutants of tRNA TRY. 4. The characterization of the adaptor mechanism of the tRNA TRY-derived alleles of the suppressor Su ion 7. 5. Characterization of solution properties which support the precision of aminoacyl-tRNA synthesis. BIBLIOGRAPHIC REFERENCES: M. Yarus, Adsorbent filters: A New Technique for Microexperimentation on Nucleic Acid, Analytical Biochemistry 70, 346 (1976). M. Yarus, Why do Organic Solvents Enhance Mistakes in Aminoacyl tRNA Synthesis? Archives of Biochem. and Biophys. 174, 350 (1976).